Compressed air control for sustainable pneumatic systems

Abstract

Compressed air is widely used in manufacturing due to the many benefits associated with its use. However, the production of compressed air is often regarded as being one of the most expensive processes in a manufacturing facility since the energy efficiency of pneumatic systems is often very low. This has become a major concern throughout industry, as the increasing energy costs and the need for more sustainable production has created a new level of competition for manufacturing companies. Thus, organizations have had to develop innovative energy efficient practices in order to remain competitive. The objective of this project was to aid in the development of energy efficient practices by focusing on increasing the efficiency of compressed air systems. This was achieved by creating several control functions that were able to mitigate the effects of different fault scenarios (leakages of different sizes, at different locations) introduced in the system. The control functions were designed to utilise simple and inexpensive control elements that are readily available, with minimal or no modifications required to the pneumatic system. To test the effectiveness of these functions, a pick and place system was used. By following an experimental procedure created by utilizing Design of Experiments, several parameters of the pneumatic system were varied according to the control functions and the resulting effects on cycle time and air consumption were recorded and analysed. Six different control functions were designed, four of which were evaluated. Three different criteria were established to analyse the effectiveness of the control functions, which were: priority to the effect on cycle time, priority to the effect on air consumption, and a balanced effect on both cycle time and air consumption. Thus, a function which best suits the requirements of a specific system could be selected, whether the most important outcome is the effect on cycle time, the effect on air consumption, or a balanced effect on both. From the data collected and the subsequent analysis, it was concluded that when prioritising the effect on cycle time, air consumption was reduced by ~9 to ~34 per cent per cycle with an increase of ~2 to ~9 per cent in cycle time. When considering the second criterion, reductions in air consumption in the range of ~24 to ~48 per cent were achieved, with an increase in cycle time in the range of ~6 to ~21 per cent. In the final criterion, reductions in air consumption in the range of ~15 to ~48 per cent were achieved, at the cost of increases in cycle time in the range of ~3 to ~11 per cent.